The tunnel timber microwave dryer is a new technology, widely used in the drying of wood, furniture, wood flooring, plywood, plywood, timber industry. In conventional drying, due to deformation, cracking, mildew and other reasons caused a lot of waste; microwave dryer with uniform heating, drying speed, not out of shape, no cracking, decay and mold, product quality, and is conducive to continuous and automated production and other advantages. The timber of microwave drying and distinctive characteristics of the heat is not an object appearance incoming, but microwave inside through the materials contained in water and wood absorb the direct heating. Due to the evaporation of surface moisture of the material, therefore, the material internal temperature is higher than the surface. Material formed within the outward pressure difference to accelerate the water surface migration. Microwave drying of wood is wet wood as a dielectric in the microwave electromagnetic field caused by the polarization of water molecules in the wet wood, alternating electromagnetic frequent strenuous exercise, causing the water molecules, generated by the friction heat, so that the wood drying .